This invention relates generally to semiconductor device packaging and specifically to a light emitting diode (xe2x80x9cLEDxe2x80x9d) containing two encapsulation layers.
Semiconductor light emitting diodes are semiconductor chips that are mounted in a package and emit radiation in response to an applied voltage or current. These LEDs are used in a number of commercial applications such as automotive, display, safety/emergency and directed area lighting. A high brightness is desired for these applications. In the conventional LEDs, in order to obtain a higher LED brightness, the current to the LED was increased. However, an increase in current also causes an increase in the LED operating or junction temperature. This increase in junction temperature undesirably reduces the LED efficiency and its operating lifetime.
The present invention is directed to overcoming or at least reducing the problems set forth above.
In accordance with one aspect of the present invention, there is provided an encapsulated device, comprising a solid state device, a first encapsulating material, and a second encapsulating material having a higher thermal conductivity than the first encapsulating material.
In accordance with another aspect of the present invention, there is provided a packaged light emitting diode, a light emitting diode chip, a lead frame electrically coupled to the light emitting diode chip, a first encapsulating material above a radiation emitting surface of the light emitting diode chip, and a second encapsulating material below the radiation emitting surface of the light emitting diode chip having a higher thermal conductivity than the first encapsulating material.
In accordance with another aspect of the present invention, there is provided a method of encapsulating a semiconductor device, comprising placing the semiconductor device into a package, placing a first encapsulating material into the package, and placing a second encapsulating material having a higher thermal conductivity than the first encapsulating material into the package.
In accordance with another aspect of the present invention, there is provided a method of encapsulating a semiconductor device, comprising placing the semiconductor device into an enclosure, simultaneously placing a first encapsulating material and a second encapsulating material having a higher thermal conductivity than the first encapsulating material into the enclosure, and wherein a specific gravity of the first encapsulating material is different than a specific gravity of the second encapsulating material such that an encapsulating material with a lower specific gravity separates above an encapsulating material with a higher specific gravity.